Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly, idempotent, non-destructive behavior, so the bar is lower. The description nonetheless adds genuine methodology context the annotations do not: savings are split into 'likely' and 'possible', are never double-counted, and costs are normalized to what the user actually pays monthly across all seats. This bounds how the agent should interpret results, though return shape is not described.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three dense sentences with no filler; the core action and the verdict taxonomy are front-loaded, and the savings/cost accounting rules follow. Some clauses ('with the arithmetic') are terse to the point of being cryptic, but nothing is wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, so the description carries the return-value burden. It enumerates the verdict labels and the two savings buckets, giving the agent a usable picture of the output, but it omits the 'skill' input's effect and any structural detail about the response, leaving minor gaps for a tool of this complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Top-level schema description coverage is 0%, so the description must compensate. It does clarify cost semantics ('what the user actually pays, monthly, all seats'), which pins down monthly_cost_usd and the meaning of seats, but it says nothing about the 'skill' enum (none/basic/technical) or how the subscriptions array should be populated beyond the sparse per-property descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific action (audit subscriptions, estimate savings) and enumerates the classification outcomes — keep, downgrade, redundant, test_replacement, review_unused, keep_critical — which makes the tool's analytical purpose concrete. It is distinguishable from siblings like recommend_stack or compare_solutions, though it never names them explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied by the phrasing 'Audit the user's subscriptions' — i.e. use it when the user has a list of subscriptions and wants savings analysis — but there is no explicit when-to-use/when-not guidance and no pointer to alternative siblings such as recommend_stack or find_alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.